Polar polysiloxane electrolytes for lithium batteries

ABSTRACT

Synthesis and electrochemical properties of a new class of polymer electrolytes based on polar polysiloxane polymers is described. Unlike ethylene oxide-based polymers, these materials are oxidatively stable up to at least 4.2 V, the operating voltage of high energy cells that use cathode materials such as lithium nickel cobalt aluminum oxide (NCA) and lithium nickel cobalt manganese oxide (NCM). Use of these polymers electrolytes as an alternative to PEO in solid-state lithium batteries is described.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. patent applicationSer. No. 15/469,481, filed Mar. 24, 2017, which is incorporated byreference herein.

BACKGROUND OF THE INVENTION Field of the Invention

This invention relates generally to electrolytes for lithium batterycells, and, more specifically, to electrolytes that are especiallysuited for use in high voltages cells.

More and more lithium battery manufacturers are using next-generationcathode materials such as NCA (lithium nickel cobalt aluminum oxide) andNCM (lithium nickel cobalt manganese oxide) in order to exploit theirpotentially high gravimetric energy densities (as high as 300-500Wh/kg), their good rate capabilities and their long-term stability.Cells made with such oxidic materials often operate at higher voltages(e.g., as high as 4.5V) than do cells (e.g., 3.6-3.8V) with olivinecathode materials such as LFP (lithium iron phosphate). Electrolytesthat have been stable at the lower voltages of LFP cells may havedifficulty operating at the higher voltages. Polyethyleneoxide (PEO)based electrolytes that are commonly used in conventional solid-statelithium batteries are known to be stable only at the lower voltages(e.g., lower than 4.0V) and may have difficulty operating at these newhigher voltages, especially in the cathode. Degradation, in the form ofoxidation, may lead to capacity fade early in the life of a cell.

Thus, there is a need to develop polymer electrolytes that arenon-PEO-based and are well-suited to operate in the high voltage (HV)conditions of next generation cathode materials.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing aspects and others will be readily appreciated by theskilled artisan from the following description of illustrativeembodiments when read in conjunction with the accompanying drawings.

FIG. 1 is a schematic illustration of one configuration of a lithiumbattery cell that contains a catholyte, according to an embodiment ofthe invention.

FIG. 2 is a schematic illustration of another configuration of a lithiumbattery cell that contains a catholyte and a cathode overlayer,according to an embodiment of the invention.

FIG. 3 is a schematic illustration of another configuration of a lithiumbattery cell that contains a catholyte, according to an embodiment ofthe invention.

SUMMARY

In one embodiment of the invention, a polymer composition includes ahomo polymer with the structure:

wherein each X is selected independently from the group consisting ofsulfone, cyanomethyl ester, sulfoxide, pyrrolidone, cyclic carbamate,phosphonate, phosphate, carbonate and perfluoroalkyl groups; each R isselected independently from the group consisting of methyl, ethyl,n-propyl, isopropyl, tert-butyl, n-butyl, n-hexyl, 2-ethylhexyl,cyclohexy, vinyl, allyl, propargyl, norbornene, cyclopentadienyl,nitroxide, bromo-isobutry bromide, 2,2,6,6-tetramethyl-1-piperidinyloxy,n-tertpbutyl-n-(2-methyl-1-phenylpropyl)-O-(1-phenylethyl)hudroxylamine),hydride, azido propyl, mercaptopropyl, benzophenone, aminopropyl,phenyl, benzyl, napthalene, anthracene styrene, acylate, norbornene,epoxide groups and substituted moieties of phenyl, benzyl, napthalene,anthracene groups, styrene, acylate, norbornene, and epoxide groups, inwhich the substituting species are methyl, ethyl, propyl, n-butyl ort-butyl groups; and z is an integer that ranges from 2 to 1000.

In another embodiment of the invention, a polymer composition includes acopolymer with the structure:

wherein each X is selected independently from the group consisting ofcyano, sulfone, sulfoxide, cyanomethyl ester, pyrrolidone, cycliccarbamate, phosphonate, phosphate, carbonate and perfluoroalkyl groups;each R is selected independently from the group consisting of methyl,ethyl, n-propyl, isopropyl, tert-butyl, n-butyl, n-hexyl, 2-ethylhexyl,cyclohexy, vinyl, allyl, propargyl, norbornene, cyclopentadienyl,nitroxide, bromo-isobutry bromide, 2,2,6,6-tetramethyl-1-piperidinyloxy,n-tertpbutyl-n-(2-methyl-1-phenylpropyl)-O-(1-phenylethyl)hudroxylamine),hydride, azido propyl, mercaptopropyl, benzophenone, aminopropyl,phenyl, benzyl, napthalene, anthracene styrene, acylate, norbornene,epoxide groups and substituted moieties of phenyl, benzyl, napthalene,anthracene groups. styrene, acylate, norbornene, and epoxide groups, inwhich the substituting species are methyl, ethyl, propyl, n-butyl ort-butyl groups; and m and n are integers, and the sum of m and n rangesfrom 2 to 1000.

An electrolyte salt may be added to either the polymer or the copolymershown above to make them useful as electrolyte materials. Examples ofuseful salts are listed below. In one arrangement, the electrolyte saltis a lithium salt.

In another embodiment of the invention, a block copolymer compositionincludes an ordered nanostructure that includes a matrix of firstdomains formed by an association of first polymers and second domainsformed by an association of second polymers. The first polymers and thesecond polymers form first copolymers. The first copolymers are blockcopolymers in which the first polymers form first blocks and the secondpolymers form second blocks. The first blocks include one or more of ahomopolymer and a copolymer with the following structure

wherein each X is selected independently from the group consisting ofcyano, sulfone, cyanomethyl ester, sulfoxide, pyrrolidone, cycliccarbamate, phosphonate, phosphate, carbonate and perfluoroalkyl groups;each R is selected independently from the group consisting of methyl,ethyl, n-propyl, isopropyl, tert-butyl, n-butyl, n-hexyl, 2-ethylhexyl,cyclohexy, vinyl, allyl, propargyl, norbornene, cyclopentadienyl,nitroxide, bromo-isobutry bromide, 2,2,6,6-tetramethyl-1-piperidinyloxy,n-tertpbutyl-n-(2-methyl-1-phenylpropyl)-O-(1-phenylethyl)hudroxylamine),hydride, azido propyl, mercaptopropyl, benzophenone, aminopropyl,phenyl, benzyl, napthalene, anthracene styrene, acylate, norbornene,epoxide groups and substituted moieties of phenyl, benzyl, napthalene,anthracene groups. styrene, acylate, norbornene, and epoxide groups, inwhich the substituting species are methyl, ethyl, propyl, n-butyl ort-butyl groups; z is an integer that ranges from 2 to 1000; and m and nare integers, and the sum of m and n ranges from 2 to 1000.

The second blocks may include one or more polymers such as polystyrene,hydrogenated polystyrene, polymethacrylate, poly(methyl methacrylate),polyvinylpyridine, polyvinylcyclohexane, polyimide, polyamide,polypropylene, polyolefins, poly(t-butyl vinyl ether), poly(cyclohexylmethacrylate), poly(cyclohexyl vinyl ether), poly(t-butyl vinyl ether),polyethylene, poly(phenylene oxide), poly(2,6-dimethyl-1,4-phenyleneoxide) (PXE), poly(phenylene sulfide), poly(phenylene sulfide sulfone),poly(phenylene sulfide ketone), poly(phenylene sulfide amide),polysulfone, polyvinylidene fluoride, and copolymers that containstyrene, methacrylate, or vinylpyridine.

In another embodiment of the invention, an electrolyte material includesan electrolyte salt and a homo polymer with the structure:

wherein each X is selected independently from the group consisting ofcyano, sulfone, cyanomethyl ester, sulfoxide, pyrrolidone, cycliccarbamate, phosphonate, phosphate, carbonate and perfluoroalkyl groups;each R is selected independently from the group consisting of methyl,ethyl, n-propyl, isopropyl, tert-butyl, n-butyl, n-hexyl, 2-ethylhexyl,cyclohexy, vinyl, allyl, propargyl, norbornene, cyclopentadienyl,nitroxide, bromo-isobutry bromide, 2,2,6,6-tetramethyl-1-piperidinyloxy,n-tertpbutyl-n-(2-methyl-1-phenylpropyl)-O-(1-phenylethyl)hudroxylamine),hydride, azido propyl, mercaptopropyl, benzophenone, aminopropyl,phenyl, benzyl, napthalene, anthracene styrene, acylate, norbornene,epoxide groups and substituted moieties of phenyl, benzyl, napthalene,anthracene groups. styrene, acylate, norbornene, and epoxide groups, inwhich the substituting species are methyl, ethyl, propyl, n-butyl ort-butyl groups; and z is an integer that ranges from 2 to 1000.

In another embodiment of the invention, an electrolyte, includes anordered nanostructure comprising a matrix of first domains formed by anassociation of first polymers and second domains formed by anassociation of second polymers. The first polymers and the secondpolymers form first copolymers that may be block copolymers in which thefirst polymers form first blocks and the second polymers form secondblocks. The first blocks may include polymer selected from the groupconsisting of:

-   -   a homopolymer with the structure:

-   -   and a copolymer with the structure:

wherein each X is selected independently from the group consisting ofcyano, sulfone, cyanomethyl ester, sulfoxide, pyrrolidone, cycliccarbamate, phosphonate, phosphate, carbonate and perfluoroalkyl groups;each R is selected independently from the group consisting of methyl,ethyl, n-propyl, isopropyl, tert-butyl, n-butyl, n-hexyl, 2-ethylhexyl,cyclohexy, vinyl, allyl, propargyl, norbornene, cyclopentadienyl,nitroxide, bromo-isobutry bromide, 2,2,6,6-tetramethyl-1-piperidinyloxy,n-tertpbutyl-n-(2-methyl-1-phenylpropyl)-O-(1-phenylethyl)hudroxylamine),hydride, azido propyl, mercaptopropyl, benzophenone, aminopropyl,phenyl, benzyl, napthalene, anthracene styrene, acylate, norbornene,epoxide groups and substituted moieties of phenyl, benzyl, napthalene,anthracene groups. styrene, acylate, norbornene, and epoxide groups, inwhich the substituting species are methyl, ethyl, propyl, n-butyl ort-butyl groups; z is an integer that ranges from 2 to 1000; and m and nare integers, and the sum of m and n ranges from 2 to 1000.

The second blocks may include one or more polymers selected from thegroup consisting of polystyrene, hydrogenated polystyrene,polymethacrylate, poly(methyl methacrylate), polyvinylpyridine,polyvinylcyclohexane, polyimide, polyamide, polypropylene, polyolefins,poly(t-butyl vinyl ether), poly(cyclohexyl methacrylate),poly(cyclohexyl vinyl ether), poly(t-butyl vinyl ether), polyethylene,poly(phenylene oxide), poly(2,6-dimethyl-1,4-phenylene oxide) (PXE),poly(phenylene sulfide), poly(phenylene sulfide sulfone), poly(phenylenesulfide ketone), poly(phenylene sulfide amide), polysulfone,polyvinylidene fluoride, and copolymers that contain styrene,methacrylate, or vinylpyridine.

In one arrangement, the block copolymer composition has first blocksthat comprise the copolymer and each X is selected independently fromthe group consisting of cyano, sulfone, sulfoxide, cyanomethyl ester,pyrrolidone, cyclic carbamate, phosphonate, phosphate, carbonate andperfluoroalkyl groups.

In one arrangement, the first blocks also include an electrolyte salt,and the block copolymer composition is an electrolyte. Each X isselected independently from the group consisting of cyano, sulfone,sulfoxide, cyanomethyl ester, pyrrolidone, cyclic carbamate,phosphonate, phosphate, carbonate and perfluoroalkyl groups. Theelectrolyte salt may be a lithium salt.

In another embodiment of the invention, an electrochemical cell has ananode configured to absorb and release lithium ions; a cathodecomprising cathode active material particles, anelectronically-conductive additive, a catholyte, and an optional bindermaterial; a current collector adjacent to an outside surface of thecathode; and a separator region between the anode and the cathode, theseparator region comprising a separator electrolyte configured tofacilitate movement of lithium ions back and forth between the anode andthe cathode. At least one of the separator electrolyte and the catholyteincludes any of the electrolytes described herein. In one arrangement,the separator electrolyte and the catholyte are the same.

In some arrangements, the electrochemical cell also has an overlayerbetween the cathode and the separator region, the overlayer comprisingan overlayer electrolyte. The overlayer electrolyte may include any ofthe electrolytes described herein. In one arrangement, the overlayerelectrolyte and the catholyte are the same.

The anode may include lithium metal, lithium alloy, graphite and/orsilicon. The cathode active material particles may include one or moreof lithium iron phosphate, nickel cobalt aluminum oxide, nickel cobaltmanganese oxide, lithium manganese phosphate, lithium cobalt phosphate,lithium nickel phosphate, and lithium manganese spinel. The bindermaterial may include polyvinylidene difluoride, poly(vinylidenefluoride-co-hexafluoropropylene, polyacrylonitrile, polyacrylic acid,polyethylene oxide, carboxymethyl cellulose, styrene-butadiene rubber,or combinations thereof.

DETAILED DESCRIPTION

The preferred embodiments are illustrated in the context oforganosilicon polymers that can be combined with salts (e.g., lithium orother alkali metal salts) to create ionically conductive materials foruse in lithium battery cells and the like. The skilled artisan willreadily appreciate, however, that the materials and methods disclosedherein will have application in a number of other contexts wherehigh-voltage electrolytes are desirable, particularly where long-termstability is important.

These and other objects and advantages of the present invention willbecome more fully apparent from the following description taken inconjunction with the accompanying drawings.

All publications referred to herein are incorporated by reference intheir entirety for all purposes as if fully set forth herein. All rangesdescribed herein are meant to include all ranges subsumed therein.

In this disclosure, the terms “negative electrode” and “anode” are bothused to describe a negative electrode. Likewise, the terms “positiveelectrode” and “cathode” are both used to describe a positive electrode.

It is to be understood that the terms “lithium metal” or “lithium foil,”as used herein with respect to negative electrodes, describe both purelithium metal and lithium-rich metal alloys as are known in the art.Examples of lithium rich metal alloys suitable for use as anodes includeLi—Al, Li—Si, Li—Sn, Li—Hg, Li—Zn, Li—Pb, Li—C or any other Li-metalalloy suitable for use in lithium metal batteries. Other negativeelectrode materials that can be used in the embodiments of the inventioninclude materials in which lithium can intercalate, such as graphite,and other materials that can absorb and release lithium ions, such assilicon, germanium, tin, and alloys thereof. Many embodiments describedherein are directed to batteries with solid polymer electrolytes, whichserve the functions of both electrolyte and separator. As it is wellknown in the art, batteries with liquid electrolytes use an inactiveseparator material that is distinct from the liquid electrolyte. Suchbatteries are also included in the embodiments of the invention.

It is known that functionalities such as ethers and esters are notstable above 4 V, and functionalities such as carbonates and nitrilesare stable above 4.2 V. Therefore, for use in high voltage cells, it maybe useful for a non-PEO-based polymer electrolyte to contain onlyHV-stable functionalities such as carbonates and nitriles. However, suchstable functional groups are very polar (or have high dipole moment)and, when incorporated into polymers, may cause polymer chainstiffening, which can result in increased glass transition temperatures(Tg) and decreases ionic conductivity.

Flexible, low Tg polymers such as polysiloxane, polyethylene,polybutadiene, and polycarbosilane are ideal platforms for incorporatingHV-stable functional groups such as carbonates and nitriles because theflexibility of such polymers may balance any rigidity caused byinteraction among such functional groups. Among these low Tg polymers,polysiloxane is the best candidate in terms of the ability for syntheticmodification, high thermal stability and high oxidative stability(stable above 4.2 V).

In various embodiment of the invention, electrochemical properties for anumber of low-glass-transition-temperature (low Tg) polysiloxanepolymers with polar substituents are described. Such polar polysiloxane(PPS) polymers are oxidatively stable above 4.2 V, making them ideal foruse as electrolytes and/or catholytes in next-generation high energylithium battery cells that use cathode materials such as lithium nickelcobalt aluminum oxide (NCA) and lithium nickel cobalt manganese oxide(NCM).

Homopolymer and Copolymer Polar Polysiloxanes:

In one embodiment of the invention, the use of polar polysiloxanehomopolymer (PPSH) materials as high voltage (HV) stable electrolytesfor lithium battery cells is disclosed. In another embodiment, novelpolymeric materials based on polar polysiloxane copolymer (PPSC)materials can also be used as HV stable electrolytes. Generalizedstructures for PPSH and PPSC are shown below. Note that the PPSC may beeither a random copolymer or a block copolymer.

In the homopolymer, z is an integer that ranges from 2 to 1000, m and nare integers, and the sum of m and n ranges from 2 to 1000. X is a polargroup. Examples for X include but are not limited to cyano, sulfone,sulfoxide, cyanomethyl ester, pyrrolidone, cyclic carbamate,phosphonate, phosphate, carbonate and perfluoroalkyl groups (structuresshown below). In some embodiments of the invention, each X in thehomopolymer is chosen independently from the groups shown below, andeach X in the copolymer is chosen independently from the groups shownbelow.

in which i is the graft length and is an integer with a range of 1 to 8.

Properties such as solubility, polarity, mechanical strength andconductivity in PPSH and PPSC can be modulated by changing the graftlength, i. Larger values for i correspond to lower concentrations ofpolar groups X in the polymer. Similarly, smaller values for i,correspond to higher concentrations of polar groups X in the polymer.The concentration of polar groups X determines the dipole moment, thedielectric constant, the ability to dissolve salts, the ionicconductivity and the mechanical strength of the polymer. Higherconcentrations of X increase dipole moment, the dielectric constant, andthe ability to dissolve salts. Conductivity and mechanical propertiesmay have maxima at intermediate values of X concentration.

Polymer properties such as polarity, ionic conductivity and mechanicalstrength in PPSH and PPSC can also be adjusted by careful choice of Xgroup. For example, sulfone groups have higher dipole moments than dosulfoxide groups, so polymers that contain sulfone groups have strongerpolarity than do polymers that contain sulfoxide groups. It is also truethat, polymers that contain sulfone groups have a higher Tg and greatermechanical strength than do polymers that contain sulfoxide groups.

There are many possible groups for R. Each R in the homopolymer and inthe copolymer may be chosen independently from the groups shown below.In various embodiments of the invention, R may be any of the following:

-   -   a saturated hydrocarbon. Examples include but are not limited to        methyl, ethyl, n-propyl, isopropyl, tert-butyl, n-butyl,        n-hexyl, 2-ethylhexyl, and cyclohexyl groups.

-   -   an unsaturated hydrocarbon. Examples include but are not limited        to vinyl, allyl, propargyl, norbornene, and cyclopentadienyl        groups.

-   -   an aromatic hydrocarbon. Examples include but are not limited to        substituted and unsubstituted moieties of phenyl, benzyl,        napthalene, and anthracene groups.

-   -   -   in which Y may be a methyl, ethyl, propyl, n-butyl or            t-butyl group.

    -   a polymerizable group. Examples include but are not limited to        styrene, acylate, norbornene, and epoxide groups.

-   -   a polymerization initiator. Examples include but are not limited        to nitroxide initiators such as        2,2,6,6-tetramethyl-1-piperidinyloxy and        n-tertpbutyl-n-(2-methyl-1-phenylpropyl)-O-(1-phenylethyl)hudroxylamine)        and atom transfer radical polymerization initiators such as        bromo-isobutry bromide groups.

-   -   a cross-linkable group. Examples include but are not limited to        hydride, vinyl, azidopropyl, aminopropyl, mercaptopropyl, and        benzophenone groups.

In one embodiment of the invention, R may be any of methyl, ethyl,n-propyl, isopropyl, tert-butyl, n-butyl, n-hexyl, 2-ethylhexyl,cyclohexy, vinyl, allyl, propargyl, norbornene, cyclopentadienyl,bromo-isobutry bromide, 2,2,6,6-tetramethyl-1-piperidinyloxy,n-tertpbutyl-n-(2-methyl-1-phenylpropyl)-O-(1-phenylethyl)hudroxylamine),hydride, azido propyl, mercaptopropyl, benzophenone, aminopropyl,phenyl, benzyl, napthalene, anthracene styrene, acylate, norbornene, orepoxide groups or substituted moieties of phenyl, benzyl, napthalene,anthracene groups. styrene, acylate, norbornene, or epoxide groups, inwhich the substituting species are methyl, ethyl, propyl, n-butyl ort-butyl groups.

Properties such as solubility, ionic conductivity and lithium transportnumber can be tuned through careful choice of R groups. Polymers thatcontain bulky R groups that are hydrophobic have increasedhydrophobicity and decreased polarity, which may reduce their ability todissolve lithium salts, resulting in lower ionic conductivity. Forexample, cyclohexyl groups are larger and more hydrophobic than aremethyl groups, so polymers that contain cyclohexyl groups have weakerpolarity than do polymers that contain methyl groups. Such weakerpolarity lowers the ability to dissolve lithium salts, which decreasesthe ionic conductivity of the polymer.

Any of the PPSH and PPSC polymers disclosed herein may be used as anelectrolyte when combined with an appropriate electrolyte salt.

Polar Polysiloxane Structures

In one embodiment of the invention, a polar polysiloxane (random orblock) copolymer PPSC has two different X groups, X₁ and X₂, as shown inthe structure below.

The sum of m and n is an integer that ranges from 2 to 1000. X₁ and X₂are not the same, and each is chosen independently from the examples forX listed above. Each R is chosen independently from the examples for Rlisted above.

In another embodiment of the invention, a polar polysiloxane (random orblock) copolymer PPSC is a terpolymer (polymer with three differentrepeat units) with two different R groups, R₁ and R₂, and only one Xgroup as show in the structure below.

The sum of m and n ranges from 2 to 1000, and m and n are integers. R₁and R₂ are not the same, and each is chosen from the examples for Rlisted above. Each X is chosen independently from the examples for Xlisted above.

In another embodiment of the invention, a polar polysiloxane (random orblock) copolymer PPSC is a terpolymer with two different R groups, R₁and R₂, and two different X groups, X₁ and X₂, as shown in the structurebelow.

The sum of m and n ranges from 2 to 1000, and m and n are integers. R₁and R₂ are not the same, and each is chosen from the examples for Rlisted above. X₁ and X₂ are not the same, and each is chosen from theexamples for X listed above.

In one embodiment of the invention, a copolymer can be formed from twodistinct polar polysiloxane homopolymers and has two different R groups,R₁ and R₂, and only one X group as shown in the structure below.

The sum of m and n ranges from 2 to 1000, and m and n are integers. R₁and R₂ are not the same, and each is chosen from the examples for Rlisted above. Each X is chosen independently from the examples for Xlisted above.

In one embodiment of the invention, a PPSH has two different X groups,X₁ and X₂, and only one R group as shown in the structure below.

The sum of m and n ranges from 2 to 1000, and m and n are integers. X₁and X₂ are not the same, and each is chosen from the examples for Xlisted above. Each R is chosen independently from the examples for Rlisted above.

In one embodiment of the invention, PPSH can either be a block or arandom copolymer with two or more X and R groups.

In one embodiment of the invention, PPSC and PPSH are end-capped on bothterminal chain ends with R groups that are identical to the pendant Rgroups used elsewhere in the structures as shown below.

The sum of m and n ranges from 2 to 1000, m and n are integers, and zranges from 2 to 1000. The R groups are all the same and are chosen fromthe examples for R listed above. The X groups may or may not be thesame, and each X is chosen independently from the examples for X listedabove.

In one embodiment of the invention, PPSC and PPSH are end-capped on bothterminal chain ends with R₁ groups that are different from the pendant Rgroups, as shown below.

The sum of m and n ranges from 2 to 1000, m and n are integers, and zranges from 2 to 1000. R and R₁ are not the same and each is chosen fromthe examples for R listed above. The R groups themselves may or may notbe the same. The X groups may or may not be the same, and each X ischosen independently from the examples for X listed above.

In one embodiment of the invention, PPSC and PPSH are capped on each endwith two different R groups, R₁ and R₂, as shown below.

The sum of m and n ranges from 2 to 1000, m and n are integers, and zranges from 2 to 1000. R, R₁, and R₂ are not the same and each is chosenfrom the examples for R listed above. The X groups may or may not be thesame, and each X is chosen independently from the examples for X listedabove.

In one embodiment of the invention, PPSH and PPSC have any of thestructures shown below, in which the pendant R groups are methyl (—CH3)groups and X is a cyanopropyl group (—CH2CH2CH2-CN). The PPSC may arandom or a block copolymer. When an electrolyte salt is added, suchPPSH and PPSC polymer materials may be used as electrolytes. The sum ofm and n ranges from 2 to 1000, m and n are integers, and z ranges from 2to 1000.

In one arrangement, triblock copolymers based-on PPSC and PPSH haveend-capping on both chain ends with initiator groups such asbromoisobutryl bromide as shown in the structures below. Such initiatorgroups can be used to grow mechanically robust polymers such aspolymethylacrylates (PMA), polybutylacrylates (PBA),polymethylmethacrylates (PMMA), polystyrene (PS), polyvinylpyridine(PVP), polytert-butylstyrene (PtBS) from the end groups of PPSC andPPSH, resulting in tri- or multi-block copolymers. The sum of m and nranges from 2 to 1000, m and n are integers, and z ranges from 2 to1000.

In one arrangement, diblock copolymers based-on PPSC and PPSH haveend-capping on only one of the chain ends with an initiator group suchas bromoisobutryl bromide as shown below. Such initiator groups can beused to grow mechanically robust polymers such as polymethylacrylates(PMA), polybutylacrylates (PBA), polymethylmethacrylates (PMMA),polystyrene (PS), polyvinylpyridine (PVP), polytert-butylstyrene (PtBS)from PPSC and PPSH. The sum of m and n ranges from 2 to 1000, m and nare integers, and z ranges from 2 to 1000.

In one arrangement, brush or comb type copolymers based-on PPSC and PPSHcan be synthesized using two or more pendant initiator groups such asbromoisobutryl bromide as shown below. Such initiator groups can be usedto grow mechanically robust polymers such as polymethylacrylates (PMA),polybutylacrylates (PBA), polymethylmethacrylates (PMMA), polystyrene(PS), polyvinylpyridine (PVP), polytert-butylstyrene (PtBS) from PPSCand PPSH. In one arrangement, brush type polymers can be obtained byhaving two or more initiating groups as pendants in PPSC and PPSHmolecules. The sum of m and n ranges from 2 to 1000, m and n areintegers, and z ranges from 2 to 1000.

PPSH and PPSCs can also form random copolymers, alternating copolymers,block copolymers or graft copolymers (when R is an atom transfer radicalpolymerization initiator) with non-siloxane based polymers suchpolybutadiene (PBD), polyethylene (PE), polyphenyleneoxide (PPE), and/orpolyimide (PI), ion-conducting polymers such as polyethyleneoxide (PEO),polyphosphonate (PPN), polycarbonate (PC), polydimethylsiloxame (PDMS)and polyacrylonitrile (PAN).

In one arrangement PPSC and PPSH polymers form a cross-linkable networkwhen R (the pendant or end cap) is a crosslinkable group such asbenzophenone as shown below. The benzophenone group can be activated byUV light to generate a ketyl radial that can undergo recombination tofacilitate crosslinking of polymer chains. The X groups may or may notbe the same, and each is chosen independently from examples shown above.The sum of m and n ranges from 2 to 1000, m and n are integers, and zranges from 2 to 1000.

In another arrangement PPSC and PPSH polymers form a cross-linkablenetwork when the chain-ends are capped with a cross-linkable group suchas benzophenone as shown below. R and X are each chosen independentlyfrom examples shown above. The sum of m and n ranges from 2 to 1000, mand n are integers, and z ranges from 2 to 1000.

In one arrangement, one or more PPSH or PPCS polymers form blockcopolymers with second polymers, and together they form an orderednanostructure. The second polymers are not PPH or PPCS polymers. Theordered nanostructure may contain a matrix of first domains made up ofPPCS or PPSH polymer blocks and second domains made up of second polymerblocks. The PPCS/PPSH blocks may also include an electrolyte salt.

Conductivity of PPSH:

Impedance spectroscopy was used to measure conductivities of PPSH inwhich the pendant and end-capped R groups were methyl groups, X was acyanopropyl group and z ranges from 10 to 500. The PPSH was mixed withvarious concentrations of LiTFSI and placed as the electrolyte inaluminum symmetric cells. The measurements were made at 80° C. The datain Table I shows that PPSH has sufficient lithium ion conductivity (onthe order of 10⁻⁴ S/cm between 10 to 30 wt. % LiTFSI) at 80° C. to beuseful in lithium battery cells.

TABLE I Conductivities of PPSH at 80° C. LiTFSI Conductivity Structure(wt %) (S/cm)

10 20 30 40 50 1.2 × 10⁻⁴ 1.3 × 10⁻⁴ 1.4 × 10⁻⁴ 8.6 × 10⁻⁵ 5.8 × 10⁻⁵

Conductivity of PPSC:

Impedance spectroscopy was used to measure conductivities of PSSC inwhich the pendant R groups were methyl groups, X was a cyanopropylgroup, and the m:n ratio was 7:3. The PSSC was mixed with variousconcentrations of LiTFSI and placed as the electrolyte in aluminumsymmetric cells. The measurements were made at 80° C. The data in TableII shows that PSSC has sufficient lithium ion conductivity (on the orderof 10⁻⁴ S/cm between 10 to 30 wt. % LiTFSI) at 80° C. to be useful inlithium battery cells.

TABLE II Conductivities of PPSC at 80° C. Structure LiTFSI (wt %)Conductivity (S/cm)

10 20 30 40 1.1 × 10⁻⁴ 1.5 × 10⁻⁴ 1.4 × 10⁻⁴ 7.8 × 10⁻⁵

Voltage Stability of PPSH and PPSC Electrolyte Materials:

Cyclic voltammetry was used to test the voltage stabilities of the PPSHand PPSC electrolyte materials whose conductivities are shown in Table Iand II. The setup consisted of an aluminum working electrode, a lithiumreference electrode, and a lithium counter electrode. Solutions of PPSHin propylene carbonate (10 wt %) with LiBF₄ (10 wt % with respect toPPSH) and solutions of PPSC in propylene carbonate (10 wt %) with LiBF₄(10 wt % with respect to PPSC) were made. The solutions were subjectedto voltage sweeps from 1.38 V (open circuit voltage) to 5 V at roomtemperature, and the current responses were monitored. The onset ofsurging current at a particular voltage is considered to be the voltageat which PPSH or PPSC undergoes oxidation. Both PPSH and PPSCelectrolyte materials were found to be stable at least up to 4.2V, thestandard lithium battery cell operating voltage.

Polar Polysiloxane Electrolytes

PPS polymer materials may be used as electrolytes when they are combinedwith appropriate electrolyte salts. There are no particular restrictionson the electrolyte salt that can be used in such PPS electrolytes. Anyelectrolyte salt that includes the ion identified as the most desirablecharge carrier for the application can be used. It is especially usefulto use electrolyte salts that have a large dissociation constant withinthe polymer electrolyte. When an electrolyte is used in the cathode, itcan be referred to as a catholyte.

Examples of appropriate salts for any electrolyte disclosed hereininclude, but are not limited to metal salts selected from the groupconsisting of chlorides, bromides, sulfates, nitrates, sulfides,hydrides, nitrides, phosphides, sulfonamides, triflates, thiocynates,perchlorates, borates, or selenides of alkali metals such as lithium,sodium, potassium and cesium, or silver, barium, lead, calcium,ruthenium, tantalum, rhodium, iridium, cobalt, nickel, molybdenum,tungsten or vanadium. Examples of specific lithium salts include LiSCN,LiN(CN)₂, LiClO₄, LiBF₄, LiAsF₆, LiPF₆, LiCF₃SO₃, Li(CF₃SO₂)₂N,Li(CF₃SO₂)₃C, LiN(SO₂C₂F₅)₂, LiN(SO₂CF₃)₂, LiN(SO₂CF₂CF₃)₂, lithiumalkyl fluorophosphates (LiFAP), lithium oxalatoborate, as well as otherlithium bis(chelato)borates having five to seven membered rings, lithiumbis(trifluoromethane sulfone imide) (LiTFSI), LiPF₃(C₂F₅)₃, LiPF₃(CF₃)₃,LiB(C₂O₄)₂, LiOTf, LiC(Tf)₃, lithium bis-(oxalato)borate (LiBOB),lithium difluoro(oxalato)borate (LiDFOB), lithium-bis(perfluoroethylsulfonyl)imide (LiBETI), lithium difluoro(oxalato)borate(LiDFOB), lithium tetracyanoborate (LiTCB), and mixtures thereof.

In other arrangements, for other electrochemistries, that is forelectrochemistries in which a non-lithium metal is the basis of thecell, electrolytes are made by combining the polymers disclosed hereinwith various kinds of non-lithium salts. For example, non-lithium saltssuch as salts of aluminum, sodium, potassium, calcium, silver, barium,lead and magnesium can be used with their corresponding metals. Specificexamples of such salts include, but are not limited to AgSO₃CF₃, NaSCN,NaSO₃CF₃, KTFSI, NaTFSI, Ba(TFSI)₂, Pb(TFSI)₂, and Ca(TFSI)₂.Concentration of metal salts in the electrolytes disclosed herein rangefrom 5 to 50 wt %, 5 to 30 wt %, 10 to 20 wt %, or any range subsumedtherein.

In one embodiment of the invention, the PPS electrolytes disclosedherein are used as catholytes in lithium battery cells. With referenceto FIG. 1, a lithium battery cell 100 has an anode 120 that isconfigured to absorb and release lithium ions. The anode 120 may be alithium or lithium alloy foil or it may be made of a material into whichlithium ions can be absorbed such as graphite or silicon. The lithiumbattery cell 100 also has a cathode 140 that includes cathode activematerial particles 142, an electronically-conductive additive (notshown), a current collector 144, a catholyte 146, and an optional binder(not shown). The catholyte 146 may be any of the PPS polymerelectrolytes disclosed here. There is a separator region 160 between theanode 120 and the cathode 140. The separator region 160 contains anelectrolyte that facilitates movement of lithium ions (or another metalions that form the basis of the cell) back and forth between the anode120 and the cathode 140 as the cell 100 cycles. The separator region 160may include any electrolyte that is suitable for such use in a lithiumbattery cell. In one arrangement, the separator region 160 contains aporous plastic material that is soaked with a liquid electrolyte. Inanother arrangement, the separator region 160 contains a viscous liquidor gel electrolyte. In another arrangement, the separator region 160contains a solid polymer electrolyte.

A solid polymer electrolyte for use in separator region 160 can be anysuch electrolyte that is appropriate for use in a Li battery. Of course,many such electrolytes also include electrolyte salt(s) that help toprovide ionic conductivity. Examples of such electrolytes include, butare not limited to, block copolymers that contain ionically-conductiveblocks and structural blocks that make up ionically-conductive phasesand structural phases, respectively. In one arrangement, theionically-conductive phase contains one or more PPSs, as disclosedherein. The ionically-conductive phase may also contain PPSs incombination, such as in copolymers, with one or more otherionically-conductive polymers such as polyethers, polyamines,polyimides, polyamides, poly alkyl carbonates, polynitriles, perfluoropolyethers, fluorocarbon polymers substituted with high dielectricconstant groups such as nitriles, carbonates, and sulfones, andcombinations thereof.

The structural phase can be made of polymers such as polystyrene,hydrogenated polystyrene, polymethacrylate, poly(methyl methacrylate),polyvinylpyridine, polyvinylcyclohexane, polyimide, polyamide,polypropylene, polyolefins, poly(t-butyl vinyl ether), poly(cyclohexylmethacrylate), poly(cyclohexyl vinyl ether), poly(t-butyl vinyl ether),polyethylene, poly(phenylene oxide), poly(2,6-dimethyl-1,4-phenyleneoxide) (pxe), poly(phenylene sulfide), poly(phenylene sulfide sulfone),poly(phenylene sulfide ketone), poly(phenylene sulfide amide),polysulfone, fluorocarbons, such as polyvinylidene fluoride, orcopolymers that contain styrene, methacrylate, or vinylpyridine. It isespecially useful if the structural phase is rigid and is in a glassy orcrystalline state. Further information about such block copolymerelectrolytes can be found in U.S. Pat. No. 9,136,562, issued Sep. 15,2015, U.S. Pat. No. 8,889,301, issued Nov. 18, 2014, U.S. Pat. No.8,563,168, issued Oct. 22, 2013, and U.S. Pat. No. 8,268,197, issuedSep. 18, 2012, all of which are included by reference herein.

In another embodiment of the invention, a battery cell with a secondconfiguration is described. With reference to FIG. 2, a lithium batterycell 200 has an anode 220 that is configured to absorb and releaselithium ions. The anode 220 may be a lithium or lithium alloy foil or itmay be made of a material into which lithium ions can be absorbed suchas graphite or silicon. The lithium battery cell 200 also has a cathode250 that includes cathode active material particles 252, anelectronically-conductive additive (not shown), a current collector 254,a catholyte 256, an optional binder (not shown), and an overcoat layer258. Both the electrolyte in the overcoat layer 258 and the catholyte256 contain any of the PPS polymer electrolytes disclosed here. In onearrangement, the electrolyte in the overcoat layer 258 and the catholyte256 are the same. In another arrangement, the electrolyte in theovercoat layer 258 and the catholyte 256 are different. There is aseparator region 260 between the anode 220 and the cathode 250. Theseparator region 260 contains an electrolyte that facilitates movementof lithium ions back and forth between the anode 220 and the cathode 250as the cell 200 cycles. The separator region may include any electrolytethat is suitable for such use in a lithium battery cell, as describedabove.

In another embodiment of the invention, a battery cell with a thirdconfiguration is described. With reference to FIG. 3, a lithium batterycell 300 has an anode 320 that is configured to absorb and releaselithium ions. The anode 320 may be a lithium or lithium alloy foil or itmay be made of a material into which lithium ions can be absorbed suchas graphite or silicon. The lithium battery cell 300 also has a cathode340 that includes cathode active material particles 342, anelectronically-conductive additive (not shown), a current collector 344,a catholyte 346, and an optional binder (not shown). The catholyte 346may be any of the PPS polymer electrolytes disclosed here. There is aseparator region 360 between the anode 320 and the cathode 340. Thecatholyte 346 extends into the separator region 360 and facilitatesmovement of lithium ions back and forth between the anode 320 and thecathode 340 as the cell 300 cycles.

With respect to the embodiments discussed in FIGS. 1, 2, and 3, suitablecathode active materials include, but are not limited to, LFP (lithiumiron phosphate), LMP (lithium metal phosphate in which the metal can beMn, Co, or Ni), NCA, NCM, high energy NCM, lithium manganese spinel, andcombinations thereof. The cathode active material particles may be oneor more materials selected from the group consisting of lithium ironphosphate, nickel cobalt aluminum oxide, nickel cobalt manganese oxide,lithium manganese phosphate, lithium cobalt phosphate, lithium nickelphosphate, and lithium manganese spinel. Suitableelectronically-conductive additives include, but are not limited to,carbon black, graphite, vapor-grown carbon fiber, graphene, carbonnanotubes, and combinations thereof. A binder can be used to holdtogether the cathode active material particles and the electronicallyconductive additive. Suitable binders include, but are not limited to,PVDF (polyvinylidene difluoride), PVDF-HFP (poly(vinylidenefluoride-co-hexafluoropropylene), PAN (polyacrylonitrile), PAA(polyacrylic acid), PEO (polyethylene oxide), CMC (carboxymethylcellulose), and SBR (styrene-butadiene rubber).

Example

The following example provides details relating to synthesis of PPSHelectrolytes in accordance with the present invention. It should beunderstood the following is representative only, and that the inventionis not limited by the detail set forth in this example.

Poly(cyanopropyl)methylsiloxane was synthesized according to thefollowing scheme:

A solution of polymethylhydrosiloxane (2.2 g, 37.2 mmol), allyl cyanide(10.0 g, 148.8 mmol) in dry toluene (12 mL) was prepared and maintainedat 0° C. To the solution was added 0.5 mL of 2%platinum(0)-1,3-divinyl-1,1,3,3-tetramethyldisiloxane catalyst complex(in xylene). The solution was gradually heated to 120° C., and theprogress of the reaction was monitored using IR spectroscopy (from thedisappearance of Si—H stretching frequency at 1270 cm⁻¹). Additionalplatinum catalyst (0.2 mL) was added to the reaction mixture every 12hours until the reaction was complete. After completion of the reaction,the solution was passed through a plug of celite, and excessallylcyanide and toluene were removed by vacuum distillation. Thepolymer was dissolved in dichloromethane to make a concentratedsolution, which was then added to vigorously stirring 2-propanol toprecipitate the polymer. The polymer was then obtained by carefullydecanting 2-propanol. The polymer was dried overnight in high vacuum at50° C.

This invention has been described herein in considerable detail toprovide those skilled in the art with information relevant to apply thenovel principles and to construct and use such specialized components.However, it is to be understood that the invention can be carried out bydifferent equipment, materials and devices, and that variousmodifications can be accomplished without departing from the scope ofthe invention itself

We claim:
 1. A polymer composition, comprising: a polymer selected fromthe group consisting of a homo polymer with the structure:

and a copolymer with the structure:

wherein each X is selected independently from the group consisting ofcyanomethyl ester, pyrrolidone, cyclic carbamate, phosphonate, andphosphate groups; each R is selected independently from the groupconsisting of vinyl, allyl, propargyl, norbornene, cyclopentadienyl,nitroxide, bromo-isobutry bromide, 2,2,6,6-tetramethyl-1-piperidinyloxy,n-tertpbutyl-n-(2-methyl-1-phenylpropyl)-O-(1-phenylethyl)hudroxylamine),hydride, azido propyl, mercaptopropyl, benzophenone, aminopropyl,phenyl, benzyl, napthalene, anthracene, styrene, and acylate groups; andsubstituted moieties of phenyl, benzyl, napthalene, anthracene, styrene,acylate, and norbornene, groups in which the substituting species aremethyl, ethyl, propyl, n-butyl or t-butyl groups; z is an integer thatranges from 2 to 1000; and m and n are integers, and the sum of m and nranges from 2 to
 1000. 2. The polymer composition of claim 1 wherein thepolymer is a copolymer and each X is selected independently from thegroup consisting of cyanomethyl ester, pyrrolidone, cyclic carbamate,phosphonate, and phosphate groups.
 3. The polymer composition of claim 1further comprising an electrolyte salt, and wherein the polymer is anelectrolyte.
 4. The polymer composition of claim 3 wherein theelectrolyte salt is a lithium salt.
 5. A polymer composition,comprising: a polymer selected from the group consisting of ahomopolymer with the structure:

and a copolymer with the structure:

wherein each X is selected independently from the group consisting ofcyclic carbamate and phosphonate groups; each R is selectedindependently from the group consisting of vinyl and allyl, groups; z isan integer that ranges from 2 to 1000; and m and n are integers, and thesum of m and n ranges from 2 to 1000; and
 6. The polymer composition ofclaim 5 further comprising an electrolyte salt, and wherein the polymeris an electrolyte.
 7. An electrochemical cell, comprising: an anodeconfigured to absorb and release lithium ions; a cathode comprisingcathode active material particles, an electronically-conductiveadditive, a catholyte, and an optional binder material; a currentcollector adjacent to an outside surface of the cathode; and a separatorregion between the anode and the cathode, the separator regioncomprising a separator electrolyte configured to facilitate movement oflithium ions back and forth between the anode and the cathode; whereinat least one of the separator electrolyte and the catholyte comprisesthe electrolyte of claim
 4. 8. The electrochemical cell of claim 7 wherethe separator electrolyte and the catholyte are the same.
 9. Theelectrochemical cell of claim 7 further comprising an overlayer betweenthe cathode and the separator region, the overlayer comprising anoverlayer electrolyte, the overlayer electrolyte comprising theelectrolyte of claim
 4. 10. The electrochemical cell of claim 9 whereinthe overlayer electrolyte and the catholyte are the same.
 11. Theelectrochemical cell of claim 7 wherein the anode comprises a materialselected from the group consisting of lithium metal, lithium alloy,graphite and silicon.
 12. The electrochemical cell of claim 7 whereinthe cathode active material particles comprise one or more materialsselected from the group consisting of lithium iron phosphate, nickelcobalt aluminum oxide, nickel cobalt manganese oxide, lithium manganesephosphate, lithium cobalt phosphate, lithium nickel phosphate, andlithium manganese spinel.
 13. The electrochemical cell of claim 7wherein the binder material is selected from the group consisting ofpolyvinylidene difluoride, poly(vinylidenefluoride-co-hexafluoropropylene, polyacrylonitrile, polyacrylic acid,polyethylene oxide, carboxymethyl cellulose, styrene-butadiene rubber,and combinations thereof.